The invention relates to an organically based electrochromic component.
Electrochromic displays based on organic materials normally comprise an active electrochromic layer which, in the case of a display, is located between electrodes disposed vertically with respect to one another. Constituents of the active layer are a redox system and a dye. The application of a voltage causes the ratio of concentrations of the redox partners with respect to one another to be shifted in the material. In this reaction, protons and/or ions are liberated or bound in the material. When a voltage is applied to the material, the shift of equilibrium of the redox partners present at the two electrodes runs in the reverse direction. This can be made visible, e.g., via pH-active dye.
A principle for implementing electrochromic displays is to produce the color change not by changing the pH value in the display but to use the redox processes taking place anyway to produce high-contrast color changes by creating reductive and/or oxidative states in suitable materials. Primarily the so-called viologens and polythiophenes have become well-known as material classes in this context. German Application Number DE 10 2005 032 316 (published as WO 2007/006767 and US 2009/0040589) discloses polymeric 4,4′-bipyridinium structures separated from one another by an alkene spacer which are eminently suitable for this purpose.
The disadvantage of the hitherto known systems is that only one color change can be achieved by applying a voltage.